1. Field of the Invention
This invention relates to an image transfer and output method and an image transfer and output system. This invention also relates to an image signal input terminal and an image output terminal for use in the image transfer and output system.
2. Description of the Related Art
In various fields, such as the medical field, techniques for reading out a radiation image of an object, which has been recorded on a stimulable phosphor sheet or film, to obtain an image signal, performing predetermined image processing on the image signal, and thereafter displaying a visible image, which is reproduced from the processed image signal, on an image display device, such as a cathode ray tube (CRT) display device, or outputting the visible image on film with a printer, such as a laser printer (LP), have heretofore been utilized.
Particularly, recently, digital image processing techniques utilizing computers have been developed. Also, various image forming apparatuses (image forming modalities) utilizing the digital image processing techniques have been used in practice as the apparatuses for forming images for use in making a diagnosis, and the like. As such image forming modalities, computed tomography (CT) scanners, magnetic resonance imaging (MRI) apparatuses, computed radiography (CR) apparatuses, and the like, have been used in practice. The reproduced visible image is utilized for making a diagnosis, e.g. for investigating the presence or absence of a diseased part or an injury or for ascertaining the characteristics of the diseased part or the injury.
The CR apparatuses are radiation image recording and read-out apparatuses. With the radiation image recording and read-out apparatuses, a radiation image of an object, such as a human body, is recorded on a sheet provided with a layer of a stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet). The stimulable phosphor sheet, on which the radiation image has been stored, is then exposed to stimulating rays, such as a laser beam, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to the radiation. The light emitted by the stimulable phosphor sheet, upon stimulation thereof, is photoelectrically detected and converted into an electric image signal with photoelectric read-out means, such as a photomultiplier. Recently, the CR apparatuses are widely used in practice.
As techniques for photoelectrically detecting light emitted by a stimulable phosphor sheet, the applicant proposed techniques for detecting light emitted from opposite surfaces of a stimulable phosphor sheet and thereby detecting two image signals from the opposite surfaces of the stimulable phosphor sheet in, for example, U.S. Pat. No. 4,346,295 and Japanese Unexamined Patent Publication No. 8(1996)-116435. With the proposed techniques, two photoelectric read-out means are located respectively on opposite surface sides of the stimulable phosphor sheet. Also, stimulating rays are irradiated to the two surfaces or only to one surface of the stimulable phosphor sheet, and the light, which is emitted by the stimulable phosphor sheet when it is exposed to the stimulating rays, is photoelectrically detected on the opposite surface sides of the stimulable phosphor sheet.
Specifically, with the techniques for detecting light emitted from opposite surfaces of a stimulable phosphor sheet and thereby detecting two image signals from the opposite surfaces of the stimulable phosphor sheet, a stimulable phosphor sheet is formed by overlaying a stimulable phosphor layer on a surface of a transparent substrate, and a radiation image is stored on the stimulable phosphor sheet. The stimulable phosphor sheet, on which the radiation image has been stored, is fitted on a transparent holder, and two photoelectric read-out means are located respectively above and below the holder. In this state, the light, which is emitted from one surface side of the stimulable phosphor sheet when the stimulable phosphor sheet is exposed to the stimulating rays, is detected by the photoelectric read-out means located above the holder, and an image signal (a one surface side image signal) is thereby detected. Also, the light, which is emitted from the other surface side of the stimulable phosphor sheet when the stimulable phosphor sheet is exposed to the stimulating rays, is detected by the photoelectric read-out means located below the holder, and an image signal (an other surface side image signal) is thereby detected.
Thereafter, an addition operation is performed on the image signal components of the two image signals having been detected from the opposite surfaces of the stimulable phosphor sheet (i.e., the one surface side image signal and the other surface side image signal), which image signal components represent corresponding pixels on the one surface and the other surface of the stimulable phosphor sheet, and an addition image signal (a superposition image signal) is thereby obtained. With the addition operation, high frequency noise occurring at random in each of the one surface side image signal and the other surface side image signal can be smoothed. Also, since the emitted light is collected from the two surfaces of the stimulable phosphor sheet, the light collecting efficiency can be enhanced. As a result, a superposition image, which has good image quality with an enhanced signal-to-noise ratio, can be reproduced from the addition image signal.
Also, as techniques for obtaining radiation image information by utilizing stimulable phosphor sheets, or the like, subtraction processing (subtraction operation) techniques have heretofore been known. With the subtraction processing techniques, a plurality of radiation images are recorded under different conditions and are then read out to obtain a plurality of image signals. Thereafter, a subtraction operation is performed on the plurality of the image signals, and a subtraction image signal is thereby obtained. In this manner, a subtraction image corresponding to the difference between the plurality of the radiation images, i.e. a subtraction image in which only a pattern of a specific object part (hereinbelow referred to also as a pattern of a tissue, a structure, or the like) in the radiation images has been enhanced or extracted, is obtained. Basically, the subtraction processing techniques may be classified into a temporal (time difference) subtraction processing technique and an energy subtraction processing technique. The applicant proposed various energy subtraction processing techniques utilizing stimulable phosphor sheets in, for example, U.S. Pat. Nos. 4,855,598 and 4,896,037.
With the rapid advances made in network technology accompanying rapid advances made in communication technology and computer technology in recent years, for example, in the medical fields, there has arisen a tendency toward utilization of medical image networks, which act as image transfer systems. With the medical image networks, various image forming apparatuses, which are located in examination rooms of hospitals, or the like, and image output devices, such as image display devices and printers, which are located in consultation rooms, laboratories, and the like, are connected to each other through a network. In such cases, visible images to be used in making a diagnosis can be reproduced in the consultation rooms from image signals, which have been acquired with the image forming apparatuses located in the examination rooms.
In the image transfer systems utilizing the networks, and the like, in cases where an operation-processed image obtained from the operation processing, such as the addition operation or the subtraction operation, is to be outputted by an image output device, the operation-processed image signal, such as the addition image signal or the subtraction image signal, having been obtained from the operation processing has heretofore been transferred from an image forming apparatus to the image output device, and a visible image has heretofore been outputted by the image output device in accordance with the transferred image signal.
However, with the transfer technique described above, it is difficult to operate such that, after the image outputted by the image output device is confirmed, parameters for the operation processing, such as the addition operation or the subtraction operation, are altered, the operation processing is again performed with the altered parameters, and an image obtained from the operation processing performed with the altered parameters is again outputted by the image output device.
Therefore, such that the difficulty described above may be eliminated, it may be considered to employ a technique, wherein a plurality of image signals having been acquired with the image forming apparatus, i.e. the original image signals, are directly transferred from the image forming apparatus to the image output device, the operation processing, such as the addition operation or the subtraction operation described above, is performed in the image output device by utilizing the plurality of the transferred original image signals and in accordance with predetermined parameters, and a visible image is outputted in accordance with the operation-processed image signal obtained from the operation processing.
However, with the technique described above, wherein the plurality of the original image signals are transferred to the image output device, and the image output device performs the operation processing and outputs the operation-processed image, the problems described below occur. Specifically, no image is displayed, i.e. a displaying waiting state occurs, before the operation processing, such as the addition operation or the subtraction operation, is finished. In the displaying waiting state, a diagnosis with an image cannot be made. Therefore, an uncomfortable feeling is given to the user, and loss of time occurs.